All websites show 502 Bad Gateway.
- Unable to check any service status or manage them via systemctl including httpd - connection timed out:
# systemctl status httpd
Failed to get properties: Connection timed out
- A lot of zombie processes are shown:
top - 08:46:49 up 11 days, 1:36, 4 users, load average: 0.56, 0.42, 0.38
Tasks: 1172 total, 1 running, 286 sleeping, 0 stopped, 885 zombie
Systemd service is hung due to running with command
--deserialize. This leads to the big amount of zombie processes and Apache could not respond.
- Connect to the server via SSH.
- Check systemd service for
# ps aux | grep systemd
root 1 1.3 0.0 191124 4136 ? Ss 09:04 0:01 /usr/lib/systemd/systemd --switched-root --system --deserialize 21
Try to reboot the system. If it is not possible out of a shell - perform a hot reboot directly on the server.